1. Field of the Invention
The present invention relates generally to multichannel data processing systems and, more particularly, to a method and system for detecting magnetic media and media transport degradation during multichannel recording.
2. Background Art
Multichannel tape recording involves the writing and reading of data on more than one track on magnetic tape simultaneously. In the data processing industry, tape devices operate almost exclusively in the multichannel or multi-track environment. Multichannel recording and reading provide a high data transfer rate characterized by high tape speeds, high tape capacities, and decreasing tape thickness.
A tape drive writes data to and reads data from tape. Tape drive controllers generate data recording statistics regarding the quantities of data correction during writing and reading. The tape drive controllers provide the data recording statistics to an attached host computer. Software programs residing at the host computer process the data recording statistics to identify bad tape and/or malfunctioning tape drives. When data is written to and read from tape, the controller typically maintains a tally of various anomalous events that occur during writing (recording) and reading (reproducing). These events are typically categorized by severity and reported separately to the attached host computer for post processing.
The most severe error is a permanent error meaning that the operation that was intended to occur did not occur. The second type of error is a defect and occurs only during recording. A defect indicates that following multiple attempts of the initial recording operation, the data had to be written to another location on the tape for the intended recording operation to be completed. The third type of error is a temporary error. A temporary error indicates that multiple attempts were required for the intended recording or reading operation to be completed. Temporary errors generally indicate debris build up on the head of the tape drive. The debris build up initially causes the recording and reading errors. Multiple attempts of the intended operation cause the debris to break loose allowing the intended operation to be completed successfully. The last type of error is a correction. A correction indicates that the data block being written or read requires some amount of data correcting to correct the error using the embedded error correction code (ECC).
In the past, the quantity of data correction was expected to be low because of the relatively low tape densities. Any elevation in correction counts indicated that error margins were being reduced as more of the ECC was required to make the necessary corrections. Software programs for processing the data recording statistics flag tape for replacement and tape drives for maintenance depending on the data recording statistics. Today, the quantity of corrections is increasing as higher recording densities are being used. The quantity of corrections is increasing because narrower tape tracks are affected easily by asperities in the tape. In the past, asperities were too small to affect the wider tracks used in lower density tape. The increasing quantity of corrections cause high correction counts to be experienced during writing and reading. However, no real error margin has been lost and the ECC can easily handle the larger number of corrections. This causes the correction counts to become uninformative and less useful in determining degradation of tape and tape drives.